OP7, a novel influenza A virus defective interfering particle: production, purification, and animal experiments demonstrating antiviral potential

Marc D Hein,Yvonne Genzel,Udo Reichl,Sebastian Püttker,Dirk Benndorf,Pavel Marichal-Gallardo,Heike Kollmus,Sascha Y Kupke,Klaus Schughart

doi:10.1007/s00253-020-11029-5

Abstract

The novel influenza A virus (IAV) defective interfering particle “OP7” inhibits IAV replication in a co-infection and was previously suggested as a promising antiviral agent. Here, we report a batch-mode cell culture-based production process for OP7. In the present study, a seed virus containing standard virus (STV) and OP7 was used. The yield of OP7 strongly depended on the production multiplicity of infection. To inactivate infectious STV in the OP7 material, which may cause harm in a potential application, UV irradiation was used. The efficacy of OP7 in this material was preserved, as shown by an in vitro interference assay. Next, steric exclusion chromatography was used to purify and to concentrate (~ 13-fold) the UV-treated material. Finally, administration of produced OP7 material in mice did not show any toxic effects. Furthermore, all mice infected with a lethal dose of IAV survived the infection upon OP7 co-treatment. Thus, the feasibility of a production workflow for OP7 and its potential for antiviral treatment was demonstrated.Key points• OP7 efficacy strongly depended on the multiplicity of infection used for production• Purification by steric exclusion chromatography increased OP7 efficacy• OP7-treated mice were protected against a lethal infection with IAV

Highlights

With annual epidemics and occasionally severe pandemics, influenza A virus (IAV, list of abbreviations, Table 1) is a major human pathogen
A seed virus containing OP7 and standard virus (STV) was used for cell culture–based production, since propagation of the apparently defective OP7 relies on STV complementation
The yield of segment 7 (Seg7) OP7 viral RNAs (vRNAs) was very similar for a production MOI of 1E−2 and 1E−3; the production MOI of 1E −3 resulted in a higher infectious virus titer

Summary

Introduction

With annual epidemics and occasionally severe pandemics, influenza A virus (IAV, list of abbreviations, Table 1) is a major human pathogen. DIPs are only capable of replication upon co-infection with an infectious standard virus (STV), compensating for the missing or truncated protein. In such a co-infection scenario, STV replication is inhibited and suppressed, and mainly non-infectious DIPs are released (Frensing et al 2013; Frensing et al 2014; Tapia et al 2019; Von Magnus 1951). One explanation for this interference is the shorter DI vRNA, which may amplify faster compared with the full-length vRNA. It was suggested that DIPs can interfere with virus replication unspecifically, via the enhanced induction of innate immunity (Easton et al 2011)

Methods

Results

Conclusion